5/4 is the constant of proportionality
Substitute y=4x to the second equation:
x^2 + (4x)^2 = 17
x^2 + 16x^2 = 17
17x^2 = 17
x^2 = 17/17
x^2 = 1
x = 1 and -1
When x=1, y=4(1) = 4
When x=-1, y=4(-1) = -4
Thus the solutions would be (1,4) and (-1,-4). That would correspond to D. and A.
The box does not let me write in it....
1. Round 50.75 to 50 and 0.18 to 0.20.
50 x 0.2 = 10
2) Round 96 to 100 and 0.499 to 0.5
100 divided by 0.5 = 50
3a) Round 8.2 to 8, 6.7 to 7, and 0.46 to 0.50
8 x 7 divided by 0.50 = 112
3b) Round 23.4 to 20, 13.9 to 10, and 0.18 to 0.20
20 x 10 divided by 0.20 = 2,000
First compute the coefficient like this:

Simplifying the fraction over 4! we get:

and the variables are

. So answer

.
The correct answer is C then.